2- Characteristics of the Species Arenga pinnata (Wurmb) Merr.

​ 2.1- Description+ The plants Sugar palm (Arenga pinnata) is a medium-sized palm, reaches a height of 12 to 15 m and a diameter of 40 cm upon reaching the maturity age (more than 15 years). The trunk is covered in a black fibrous hessian like material, while the leaf bases have long spines protecting them.+ The leaves The leaves are erect, long up to 8-9 m, with linear leaflets long up to 1,5 m, irregularly indented at the extremity, inserted on the rachis with various angulations; the colour is dark green on the upper side, and greyish on the lower one. The leaf has 100 or more pairs of linear leaflets. Once maturity is reached, huge fruit clusters begin to appear.+ The flowers The spikelike flower stalks are borne among the leaves and have both male and female flowers, so a single sugar palm can produce fertile seeds by itself. The male flower, in a dense cluster of 4 ft long is purple and has an unpleasant odor. The female flower clusters are longer than the male and ripen very slowly into glossy, brown, plum sized fruit. Each new flower cluster is borne on a leaf axil. When flowering reaches the lowest leaf axil and the fruit ripens, the entire spectacle ends and the plant dies. Since each flower takes about 2 to 5 years to become a ripe fruit, fruits are always available on the trees during this period. Arenga pinnata has very numerous, crowded green nuts, which turn yellow when mature.+ The fruits Fruit is a globose to ellipsoid drupe, 5-8 cm long, fleshy, first green, later turning yellow and black after falling. The immature fruits are widely consumed in the Philippines (called kaong) and Indonesia (called buah kolang-kaling or buah tap) and are made into canned fruits after boiling them in sugar syrup.+ The seeds Each globular fruit is less than 2.5 cm (1 in) in diameter and contains one to three seeds.

2.2- Origin and Distribution+ Origin: The Sugar or Formosa palm, Arenga engleri, is native to islands south of Japan, including Taiwan (Formosa) and the Ryukyu Islands. It also has been reported from India. The Formosa palm occurs on slopes in dense forests.+ Distribution: It is widely distributed in rainforests of tropical Asia; from eastern India east to Malaysia, Indonesia, and the Philippines in the east.Widely grown in the tropics and is used to produce sugar, sago, and alcoholic drinks.

2.3- Biological characteristics+ Ecology Sugar palm grows best in warm conditions with a maximum amount of light and abundant water supply on very fertile soils. It can, however, grow under a wide variety of conditions, both in equatorial and seasonal climates, from sealevel up to 1400 m altitude, on all soil types from heavy loam to loamy sand and lateritic soils that are not regularly inundated. The growth rate drops substantially where growing conditions are less favourable. Wild in primary or secondary forests, it occurs especially on sites poor in nutrients and in marginal areas such as denuded hillsides. The age of first flowering depends strongly upon the altitude, being 5-7 years at sea-level and 12-15 years at 900 m altitude.

​ + Growth and development Germination is very unpredictable, taking from one month to more than a year, and is remote-tubular. A tube emerges from the germpore near the apex of the seed and enters the soil. The radicle and plumule appear from the side of this tube, followed by 3-4 roots which grow straight up. Soon the radicle and these early roots are overtaken by the normal adventitious roots. The rosette stage takes 3-5 years and the trunk growth phase 5-10 years, depending mainly on temperature, but also on competition for light. The rate of leaf production during trunk formation greatly depends on the growing conditions, but it is of the order of 3-6 leaves per year. Fifty leaves may be the maximum over a palm's life. The last two leaves emerge simultaneously, signalling the onset of flowering. These leaves expand fully, but the few remaining primordia and the growing point itself "petrify": they become woody without further growth. The first inflorescences emerge from the axil of the uppermost leaves and bear female flowers. Flowering gradually proceeds downwards: 3-7 female inflorescences are followed by 7-15 male inflorescences, although the latter may include a few which bear female flowers as well or which are completely female. Sometimes the formation of lower-positioned female inflorescences can be induced by removing the top female inflorescences. Buds lower on the trunk tend to be underdeveloped and in the natural state the palm dies before it is their turn to bloom. Sometimes completely male trees are encountered which are known to produce larger amounts of sugary juice (called "puso lolon" trees in North Sulawesi). The flowers are presumably crosspollinated since there is little overlap in flowering of female and male inflorescences of the same palm. Bees pollinate flowers, but small flies also swarm in large numbers around male inflorescences. Each female inflorescence carries thousands of fruits which take 12 months from flowering to maturity if the palm is not tapped. One palm may produce as many as 250 000 seeds. The trunk serves as a store for starch that is accumulated after the rosette stage in the parenchyma of the pith. When flowering starts the starch is converted into sugar and dissolved in the stem fluid. As with Metroxylon sagu Rottboell, additional sugar is produced by photosynthesis in the functional leaves. In the natural state the palm dies after the fruit of the inflorescences near the top have matured, that is about 2 years after flowering starts. Skilful tapping can extend the tree's lifespan by 10 years or more. Since a load of growing fruit is essential to keep the palm alive, few or no female inflorescences are tapped. The art of tapping is to tap so little that fruits do not starve, but to tap sufficiently to delay their maturation indefinitely. Overtapping results in the lower green leaves breaking off, followed by massive premature fruit fall and death. The sagging of these leaves is the first sign that the palm is bleeding excessively. An optimal tapping intensity maintains an adequate sap stream to the fruit, ensuring a minimal rate of fruit growth. A smallholder in North Sulawesi pointed out a tree which he had been tapping for 15 years! This implies a leaf age of more than 15 years. The extended life of the leaves under judicious tapping must contribute substantially to total sugar yield over such long periods. One documented tree produced more than 20 000 l of sugary juice within a period of three years. This represents some 12 t sugar from one tree. Ultimately, tapped trees produce fruit too; if tapping is stopped in time the unripe fruits can be used for "kolang kaling" production. The remaining starch level in the trunk is too low to make extraction worthwhile (less than 20 kg for tapped trees).